Vaccine Hesitancy

Vaccine hesitancy refers to delay in acceptance or refusal of vaccination despite the availability of vaccination services. It is not a single attitude but a spectrum running from full acceptance to outright refusal, and it varies by vaccine, place, and time. Because it concerns people who could be vaccinated but hesitate, it is analytically distinct from access barriers that prevent willing people from being immunized.

Definition

Vaccine hesitancy is delay in acceptance or refusal of vaccines despite availability of vaccination services; it is context-specific, varies across vaccines and settings, and is influenced by factors such as complacency, convenience, and confidence.

Scope

This topic covers how hesitancy is defined and measured, its principal determinants, and the way researchers distinguish it from both access barriers and organised anti-vaccine opposition. It treats hesitancy as a behavioural and social phenomenon and a reference subject; it does not prescribe how to counsel individual patients or design specific interventions.

Core questions

• How is hesitancy defined and distinguished from refusal and from access barriers?
• What are its main determinants, and how do they vary by context?
• How is hesitancy measured across populations?
• What does the evidence say about whether and how it can be addressed?

Key concepts

• Hesitancy as a continuum from acceptance to refusal
• Vaccine confidence
• Complacency and perceived disease risk
• Convenience and structural ease of access
• Context-specificity (vaccine, place, time)
• Trust in providers and institutions
• Distinction from organised anti-vaccine movements

Key theories

3Cs model (confidence, complacency, convenience)

The WHO SAGE Working Group framework, articulated by MacDonald, organises the determinants of hesitancy into confidence in vaccines and providers, complacency (low perceived risk of disease), and convenience (the ease of accessing vaccination), providing a common structure for describing and comparing hesitancy across settings.

Mechanisms

Hesitancy arises where the perceived benefits of vaccination are outweighed, for a given person in a given context, by perceived risks, low perceived threat from the disease, distrust, or practical friction. The 3Cs framework treats confidence, complacency, and convenience as the proximal determinants, while Larson and colleagues emphasise that confidence is dynamic and shaped by information environments, social networks, and historical experience with health systems. Because the balance differs by vaccine and setting, the same person may accept one vaccine and decline another, and population-level hesitancy can shift rapidly in response to events.

Clinical relevance

Recognising that under-vaccination may reflect hesitancy rather than lack of access helps clinicians and public-health workers interpret uptake patterns and understand the determinants at play. This entry describes the phenomenon and its determinants as a reference; it does not provide a protocol for individual counselling or specify interventions.

Epidemiology

Systematic reviews find that hesitancy is reported worldwide but its prevalence, intensity, and specific drivers vary widely by region, vaccine, and period. Reviews of interventions report mixed and context-dependent effects, with no single approach reliably effective across settings, underscoring the context-specific nature of the phenomenon.

Evidence & guidelines

The dominant analytic framework is the WHO SAGE Working Group's definition and 3Cs model summarised by MacDonald. Systematic reviews by Larson and by Jarrett map determinants and catalogue intervention strategies respectively, while meta-analytic and review syntheses (Xiao; Dubé) examine psychological correlates and longer-term trends. This entry summarises these reference sources rather than issuing recommendations.

History

Reluctance toward vaccination is as old as vaccination itself, but the modern concept of vaccine hesitancy was consolidated in the 2010s, notably through the WHO SAGE Working Group on Vaccine Hesitancy, whose 2015 definition and 3Cs model gave the field a shared vocabulary. Larson and colleagues' earlier framing of a vaccine confidence gap and their systematic reviews helped move the discussion from anecdote to measurable determinants.

Debates

Can hesitancy be reliably reduced by communication interventions?

Systematic reviews find that intervention effects are inconsistent and highly context-dependent, and there is debate over whether information-focused approaches suffice or whether trust and structural factors must be addressed, with no approach reliably effective across settings.

Key figures

• Noni MacDonald
• Heidi Larson
• Ève Dubé

Seminal works

• macdonald-2015
• larson-2014
• jarrett-2015

Frequently asked questions

Is vaccine hesitancy the same as refusing all vaccines?

No. Hesitancy is a continuum: a hesitant person may delay, accept some vaccines and decline others, or eventually accept after deliberation. Outright refusal of all vaccines is one end of the spectrum, not the whole of it.

What are the 3Cs of vaccine hesitancy?

In the WHO SAGE framework the 3Cs are confidence (trust in vaccines and providers), complacency (low perceived risk of the disease), and convenience (how easily vaccination can be accessed).